Lung infection

Question 1

What are types of multi-layered defence mechanisms?

Answer 1

Mechanical
Local
Systemic

Question 2

Give example of mechanical

Answer 2

Pathogens stick onto the mucus within the airways (hairs in the nose also filter things out)

Question 3

examples of local?

Answer 3

Bronchus associated lymphoid tissue (BALT)- there is an immune system within the respiratory tract that samples antigens that you inhale and produce antibody to neutralise it.

Question 4

what happens if a bug gets past the mechanical and local defences?

Answer 4

• Call upon defences from the circulation (polymorphonuclear leukocytes).
• Neutrophils can mobilise themselves from the circulation, move into the airways and attack the infectious agent

Question 5

What structures knit the epithelia into a cohesive layer?

Answer 5

Tight junctions

Question 6

what type of cell produces mucus

Answer 6

Epithelium is made up of ciliated cells and goblet cells which produce mucus along with submucosal glands.

Question 7

Describe the two layers of fluid surrounding and above the cilia.

Answer 7

Watery periciliary fluid

Mucus (thick and gel-like)

Question 8

How fast does each cilium beat?

Answer 8

15 times per second

Question 9

Describe how the cilium is withdrawn after the forward stroke.

Answer 9

It is withdrawn in a curved fashion within the periciliary fluid and under the mucus so that it doesn’t pull the mucus back in the opposite direction.

Question 10

Describe the rhythm of the cilia.

Answer 10

Metachronal rhythm

Question 11

Describe the ultrastructure of the cilium.

Answer 11

It has a 9+2 structure - it has 9 microtubule pairs around the outside and two microtubules in the middle
The outer microtubule pairs have inner and outer dynein arms

Question 12

What enables the cilia to move?

Answer 12

ATPase on the dynein arms, which provides energy for the microtubules in the cilium to move up and down each other to make the cilia bend

Question 13

what 2 things must you take into consideration if someone presents with chest infection?

Answer 13

• the infection itself

- the host defences

Question 14

Give two examples of acquired defects of the mucociliary system.

Answer 14

Smoking and

Viral infections

Question 15

Why do bacterial infections often follow viral infections?

Answer 15

Viruses can damage the epithelia allowing the bacteria to dock down and colonise

Question 16

What can happen to the cilia when they grow back?

Answer 16

They can regrow abnormally and form compound cilia, which are useless

Question 17

What is the relationship between cilia and dextrocardia?

Answer 17

50% of people born without functioning cilia have dextrocardia
This is because the micro-tubules are involved in guiding cells around during embryological development.

in some patients, there is an inner dynenin arm but NO outer dynenin arm. This is the DYNEIN ARM EFFECT

Question 18

how does dectrocardia look on an x-ray?

Answer 18

-the side of the body that the heart is on is RANDOM

Question 19

What is the term given for congenital disease causing malfunctioning cilia? How does this disease affect the ultra-structure of the cilium?

Answer 19

Primary ciliary dyskinesia - this is caused by a dynein arm defect

Question 20

What biochemical marker is used to assess risk of primary ciliary dyskinesia before performing nasal biopsy?

Answer 20

People with primary ciliary dyskinesia have lower levels of nasal nitric oxide than people without.

Question 21

What is the most common cause of bronchitis and sinusitis?

Answer 21

Haemophilus influenza

Question 22

What parts of the epithelium does bacteria stick to?

Answer 22

Damaged areas of epithelium - they do not stick to the ciliated epithelium

Question 23

How does pneumonia look like on an x-ray and what happens in pneumonia?

Answer 23

-There is pneumonia in the superior lobe of the right lung
-this is actually SOLID lung: the alveoli are full of pus.
-alveoli are full of pus
pus= debris of the host trying to fight the infection

Question 24

what are the clinical features of pneumonia?

Answer 24

• cough
• sputum
• fever
• dysponoea
• pleural pain
• headache

-get a stabbing pleuritic chest pain

Question 25

what is special about the bacteria that causes pneumonia?

Answer 25

• it has a polysaccharide capsule around it
• the capsule is negatively charged, which makes it more difficult for the bug to bind to the epithelium but it also makes it much more virulent and able to invade the bloodstream and cause systemic infection.

Question 26

What happens to the protease and anti-protease ratio in chronic inflammation?

Answer 26

During phagocytosis, a little bit of protease gets spilled into the surrounding secretions.

• usually there are anti-proeases to neutralise the enzyme and stop it causing damage
• in chronic there are so many neutrophils in the lungs and so much protease is released that the protease enzyme overwhelms the antiproteases. As the antiproteases are overwhlemed, you get FREE PROTEASES sitting in the yellow-green sputum, which causes damage.